Circuit breaker



S- 1937K H. MILLIKEN CIRCUIT BREAKER Filed Feb. 12, 1935 11 Sheets-Sheet 1 nm umm l N VENTOR EMZZZZEUL J0. IIIIIIIIHII ATTORNEYS Y. H. MILLIKEN 2,089,286

CIRCUIT BREAKER Filed Feb. 12, 1955 I 11 Sheets- Sheet 2 1937. H. MILLIKEN 2,089,286

0111011111 BREAKER I Filed Feb. 12, 1955 11 Sheets-Sheet s 8-1 l- L MILLIKEN I 2,089,286

1 CIRCUIT BREAKER Filed Feb. 12, 1935 '11 Sheds-Sheet 4 1937- H. MlLLlKEN 2,089,286

' CIRCUIT BREAKER Filed Feb. 12, 1935 ll Sheets-Sheet 5 0, 1937. H. MlLLlKEN CIRCUIT BREAKER Filed Feb. 12. 1935 ll Sheets-Sheet 6 IIIIHIHIIIHHHIH? A5" Rem-mus Aug. 10, 1937.-

H. MILLIKEN CIRCUIT BREAKER Filed Feb. 12, 1935 ll Sheeis-Sheet '7 W v H Mmfliep Aug. 10, 1937. H. MILLIKEN 2,089,286

CIRCUIT BREAKER Filed Feb. 12; 1935 11 Sheets-Sheet s H. MILLIKEN CIRCUIT BREAKER Filed Feb. 12, 1935 Aug. 10, 1937.

11 Shee ts-S heet 9 H. Ml LLlKEN cmcun BREAKER I Filed Feb. 12, 1935 11 Sheets-Sheet 1O ,5 I'M i i A 47 mmmlmunmww 7 3mm I Jag/6 BM Patented Aug. 10, 1937 UNITED STATES cmcm'r BREAKER Humphreys Milliken, Mount Royal, Quebec, Canada Application February 12, 1935, Serial No. 6,236

20* Claims.

This invention relates to circuit breakers for interrupting heavy short-circuit currents in large power systems. More particularly the invention relates to improvements in gas blast circuit '5 breakers for interrupting heavy short-circuit currents.

An important object of the invention is to provide improved means for operating such a circuit breaker.

Other objects of the invention will appear hereinafter.

In the drawings, Fig. 1 is a view showing diagrammatically an arrangement of switches; operating mechanism and circuit connections employed in the circuit breaker;

Fig. 2 an end view of the circuit breaker;

Fig. 3 a side view of the circuit breaker em bodying three poles for ,handling a three-phase Fig. '7 a vertical section through the inter-- rupter, taken approximately on the line VIIVII of Fig. 5;

Fig. 8 a vertical section through the interrupter, taken approximately on the line VIII-VIII of Fig. 5;

Fig. 9 a horizontal section through the interrupter, taken approximately on the line DI-IX of Fig. 8;

' Fig. 10 a detail cross-sectional view of the rockable impeller for operating the transfer or by-pass switch and showing a portion of the tubular impeller shaft.

Fig. 11 a sectional side elevation of the mechanism for opening the by-pass or transfer switch;

Fig. 12 a sectional plan view of the mechanism for opening the by-pass or transfer switch;

Fig. 13 a vertical sectional view of the mechanism for closing the by-pass or transfer switch;

Fig. 14 a side elevation of the disconnecting switch and showing the operating mechanism therefor, partly in elevation and partly in section; V

Fig. 15 a plan view of the disconnecting switch and its operating mechanism, the latter being partly in section;

Fig. 16 a vertical sectional view of the gas blast control valve mechanism and including a portion of the electrical connections for operating said mechanism;

Fig. 17 a detail vertical sectional view of a bypass valve employed in associationwith the main gas blast valve; and

Fig. 18 a wiring diagram for the three-phase circuit breaker. 5

As shown diagrammatically in Fig. 1, the circuit-breaking apparatus for each phase of the circuit includesa current interrupter K, a main disconnecting switch I and a by-pass or transfer switch 3. These are all operable in a desired 10 sequence in response to a blast of air or other suitable gas. For supplying said blast, there is provided a storage tank '8 .for compressed air.

A valve device 9 is secured to said tank, and a blast tube or conduit l0 leads from' the valve and 15 is in delivery connection with the current interrupter K. The valve is electrically operable in response to an overload in the main circuit to admit a blast of air from the tank I to the conduit through which it is delivered to the current no interrupter to open the latter and also extinguish arcs therein. There are also connected to the conduit a mechanism L to open the disconnecting switch I, and a mechanism M to open the bypass switch 3. These mechanisms are also op- 25 erable in response to the air blast in the conduit.

In Fig. 1 theinterrupter K, the by-pass switch 3 and the disconnecting switch I are all indicated in closed position. High-tension alternating current may be considered as coming in from the 0 main line at the left, through the disconnecting 3 switch I, flexible conductor 2, the by-pass switch 3, a flexible conductor 4, a transformer 5, and out through the main line at the right. The interrupter is in shunt with the by-pass switch 35 3, and normally the flow of current is through the switch 3. instead of the interrupter. The transformer 5 has three secondary windings. One winding has a relay connection for operating the valve 9 to open it, inresponse to an overload in the main circuit, and admit an air blast to the *9 conduit Ill. The purpose of the other secondary windings will appear hereinafter. In the conduit the blast iirst actuates the mechanism M to open the by-pass switch. Thereby the current is shunted to the interrupter K. The latter is next opened and the arcs therein are extinguished by the air blast. After the air blast has opened the interrupter it eifects the opening of the disconnecting switch I, through the mechanism L. r The by-pass switch and the disconnecting switch break no current (except that the latter breaks a very small current under conditions hereinafter described). The current is broken by the interrupter K, which is particularly adapted to 55 perform this function. a

The air blast also sets in operation a means for closing the air valve 9. The by-pass switch 3 and the interrupter K are returned to closed position by springs. The disconnecting switch i is left open. Therefore, as soon as the switch I is closed the apparatus will be in condition to reopen properly and immediately in case it is required to open by reason of a fault existing on the power system.

Figs. 5, 6, 7, 8, and 9 show, in detail, the structure of the interrupter. It is a built-up structure comprising a stack of similar, fiat, superposed units. Said units may be stacked up in greater or less number, in accordance with the voltage which the interrupter is required to handle. In the present instance, there are twelve of the stacked units in each interrupter. Each unit comprises a body B of insulation recessed to define an aperture or vertical bore 60, a diifusion chamber l1 and a pair of horizontal arcuate passages or are chutes i3 connecting said bore and chamber. The body B may be formed of groups of horizontal sheets cemented together. All groups are bolted together by twenty vertical rods of insulating material. A pair of arcing horns l5 are pivotally mounted within the diffusion chamber to swing horizontally and they are electrically connected and connected to swing in unison. Each horn comprisese a radial arm leading from the pivotal mounting of the horn and bearing an arcuate portion which extends through one of the arc chutes lit. The bores 50 of the successive interrupter units are disposed in register to form a vertical air conduit leading to the top of the interrupter. The air blast pipe 10 is in delivery communication with the lower end of said conduit, and the conduit is in lateral communicationwith all of the arc chutes. While the arc chutes, and the members ii are, in the present instance, curved, they may be rectilinear and the members it may move along a straight line instead of an arc.

The insulator bodies of the interrupter units are also recessed to shiftably accommodate contactors I2. The latter are arranged laterally or transversely of the horns i6 and are disposed to project into the arc chutes and bear laterally against one side of the tip portion of the horns, when the horns are in closed-circuit position. Said tip portions are tapered to provide a flare for admission of the air blast from the aperture 80. A spiral spring I! at the pivotal mounting of each pair of horns urges the horns to circuitclosing position. Each contactor i2 is also spring-urged laterally into contact with its cooperating arcing horn or electrode. Alternate contacts II are electrically joined in pairs to form with the horns a zig-zag current path throughout the full height of the interrupter structure.

The actual arc chute occurs between the outer arcuate wall of the horn l6 and the opposed insulation wall. The chute so defined is quite narrow and its cross-section is only about three quarters of a square inch. This is desirable for the reason that the small cross section ofthe chute has an important effect upon the efficiency of the arc extinction under the air blast. The horn forms a movable wall of the chute and it is essential that this wall be of conducting material and form part of the high-tension circuit in order that one end of the arc current path shall be swept rapidly away from its other end to stretch its length andreduce its conductivity to zero in minimum time and with minimum air supply to the arc chute. Each are chute 3 1 ql 0 inch depth vertically, and the horn which moves in it is of about seven-eighths inch depth. Each pair of arc chutes opens into the diffusion chamber H. The latter is about four inches in depth and has a horizontal area of about six square feet. The diffusion chamber has an outlet to atmosphere, and a cooling grid II is disposed across the path of air to the outlet. Said grid may be formed of sheets or strips of copper closely spaced. At the outlet, there is a closure in the form of a hinged damper IS. The latter is normally closed but is adapted to be swung open by the air blast and to be reclosed by its own weight.

The outer stationary insulation wall of each arc chute has a resistor contact l4 spaced inward along the chute from the contactor I2, and out of contact with the horn IS. A current-reducing resistor I5 is connected to each contact it. There is in the interrupter one resistor l5 for each horn l8. Each comprises granulated carbon packed in insulating tubes and held under compression by a spring. Each of said resistors -is also connected to a second resistor I5 of higher ohmic value.

'All surfaces of the interrupter with which the warm, dry air is allowed to pass through the interrupter continuously. Clean, dry air is produced by passing it through a pad of wool which removes the oil vapor (from the compressor lubrication), and then through a bed of activated alumina, which removes the moisture vapor to such a degree that the dew point is reduced to about 35 F. below zero. The wool and alumina are packed in the same container in the powe house. A

The four sides of the interrupter are covered by vertical sheets of "Armourplate" glass one quarter inch thick, a heat-treated material which is very resistant to shock. This insulating surface is vertical, and has inclined shields, or skirts. It is, therefore, fully protected from the accumulation of a conducting path of snow, dust, soot, etc., which would occur if the surfaces were horizontal, and cause a flashover upon interruption or a short-circuit. The sides are readily removable for access to all interior parts, including the contacts, which can be easily removed when re quired.

A fundamental advantage of the interrupter is that the entire range of commercial voltages, (from 12,000 upward), can be properly served with one design of interrupting element or unit only six inches high and four feet square. A large number of these elements can be stacked up in a relatively small space; for 138,000 volts, the stack will be only about forty inches high, and for 275,000 volts about seven feet high. When higher voltages are required, they can be served by simply adding more of the same units.

The interrupter assembly K, the by-pass switch 3, and the blade of the disconnecting switch i are all supported on eight stacks of standard switch insulators in a zig-zag truss formation around the space beneath the interrupter, to eliminate cantilever stresses on the stacks and to provide rigidity. The stacks rest in a structural steel frame embedded in concrete, for rigid anchorage. The compressed air storage tank 8 rests on the same concrete foundations and has three of the air blast valves 9, one for each phase, connected to the three interrupters K by the three porcelain air blast tubes I0, of six-inch internal diameter. The valves 3 are opened and closed electro-pneumatically, the energizing coils,

discussed hereinafter, taking lessthan t'en amtactor I2, or moves it away from the horn I6 about one-half of an inch. The contactor has less resistance to movement than the horn and, therefore, moves away from the horn before the latter commences to move under the impact of the blast. Separation of the contactor I2 from the horn causes an arc and the blast blows the short are along the narrow horizontal passage I3. The are touches the resistor contact I4 and shunts the resistor in circuit. This shunts the current out of the arc, reduces the total current, and brings the current practically into phase with the voltage, facilitating current interruption and practically eliminating voltage surges. While one end of the arc remains on the contact II, the other end is blown by the air along the metal horn I6. Thereby the arc is stretched and subjected to the conduction-reducing effect of the air blast throughout its length. The conditions at this moment are ideal for the breaking of the arc, viz: The cross'section of the arc cannot be greater than that of interrupter of current occurs before the horn l6 has reached its outermost position. All of the horns are held in that position by the air blast, putting between the twenty-four open contacts an aggre ate separation of about twenty-four feet and giving a large factor of safety against restriking of the arc while the disconnecting switch is opening (about one-quarter of a second). When the air blast is shut oif, the horns l6 and contacts I2 are returned to their closed position by their respective springs. The cooling "grids I8 remove any remaining incandescent heat without impeding the free passage of air.

The duration of the current through each resistor I is about one half .cycle, and the resistors never rise in temperature more than 10 C. The ohmic value of the resistors is based upon a system impedance corresponding to a maximum (rated) interrupting capacity of the breaker, so that the current is reduced to almost the same value, regardless of the amount of the initial short-circuit current. The second resistor I5 is of much higher ohmic value (about 100,000 ohms). There is one resistor ISI for each resistor I5, all being connected in series to produce a uniform potential gradient through the interrupter and overcome electro-static effects which would otherwise give a non-uniform gradient.

The by-pass or transfer switch 3, and its operand 2. The switch 3, in its normal closed position is inclined and its upper end is pivotally supported by an inclined conducting arm I. The latter is in turn supported at its upper end by the interrupter K. The switch is opened by impact of the air blast upon an impeller vane IIIl. Said vane is pivotally mounted within a'casing connected to the blast pipe I0, preferably to the upper end of the latter and forming a direct air flow connection between the pipe and the vertical conduit formed by the vertical bores 60 of the interrupter. As shown in Fig. 11, the impeller casing comprises two parts, I22 and I23, held together by bolts I21. the container 8, via the valve 9, passes upward through the casing. Normally the air blast passage is closed by the vane I I0. The vane is curved in cross section, as shown in Fig. 10, so that in its open position it will fit snugly against one side of the interior of the casing and ofier no obstruction to the passage of the air blast. The casing is bulged out. slightly, following the arc of a circle, so that the vane may have a greater The air blast from area and'also maintain its closure of the blast passage through a maximum portion of its upward swing, in orderto impart a maximum impulse and open the switch 3 as quickly as possible. At the lower end of the casing section I22 is an expansion sleeve I 30, preferably of bronze, to take up slack in the insulating blast tube I 0 due to the compressibility of gaskets between sections, of which the tube is forward. Heavy adjusta-ble springs I3I maintain suitable pressure on the gaskets to prevent their being blown out or displaced by the pressure of the air blast.

- The impeller vane III) is welded to a hollow shaft I I I mounted to rotate in two bearings on an axis disposed in the same horizontal plane as the joint between the parts I22 and I23 of the impeller casing. That permits installation and removal of the vane and its shaft tog-ether with cranks I I2 and H3 which are welded to the shaft outside of the casing. The purpose of the welding is to obtain necessary strength with minimum weight, for maximum acceleration in opening. There are two pairs of the cranks H2 and H3, at opposite ends of the shaft III. Between the outer ends of each pair there is pivoted a sleeve II'I. terial, such as impregnated hickory, is rigidly secured at one end to each sleeve and extends axially therefrom, with the interior of the sleeve vented axially at one end along the rod. At their opposite ends said rods bear against a cross-bar A rod I I4 of insulating ma- 1 30 of insulating material, bolted to the switch blade 3; Two contacts 3| are rigidly secured to the switch 3 and each engages a pair of jaws 32 and 33'. These are pressed toward each other by a spring 35 on a bolt 34 extending through the jaws. This provides high-pressure electrical contact on both edges of the contact bar 3|. The jaws 32 and 33 are secured to a shaft 4 mounted to turn in bearings 4| borne by the impeller casing. A crank 36 is secured to the shaft 40. and an extensible link 31 connects the outer end of said crank to a short crank, extending diametrically from one of the cranks II3. Said link contains a compression spring 38 which is compressed when the link is stretched. The jaws 32 and 33 are shown in the closed position of the by-pass switch, in which position the link 31 is stretched.

The tubular impeller shaft Iii has an air port within the impeller casing, and bent pipes H6 lead from the opposite ends of, the shaft ill to the sleeves Ill, surrounding one end of the rods Ill. These connections provide for delivery of a blast of air coaxial with each rod Illalong its entire length.

The arm or bracket ,1 which hingedly supports the by-pass switch bears an air cylinder 50 and piston 5i. The piston has a rod extending from the lower end of the cylinder and providedwith a transverse slot 55. A pin 54 borne by the bypass switch and ofi'set from the pivot of the latter projects through said slot. Between the lower end of the cylinder and the piston, there is a compression spring 51 tending to move the piston upward and swing the switch to closed position. A pipe 52 leads from the upper end of the vertical air conduit of the interrupter to the upper end of the cylinder 50 to lead air pressure to the piston for forcing the latter downward and holding the switch open, against the resistance of spring 51, until the air blast is shut oil. In order to delay closure of the switch 3, the pipe 52 is provided with a check valve 55 having a swinging valve disk 59 normally swung downward to open position. Said disk is adapted when closed to permit slow leakage upward through the pipe.

The mechanism M, just described, for operating the by-pass valve works as follows: The air blast released by the valve 9 strikes the vane H0 and swings the latter upward and to the right, with reference to Fig. 11. Cranks [l2 and H3 are swung and push the rods ill against the cross arm 30 and swing the switch 3 to the right. Jaws 32 and 33 are rotated clockwise by the contact bars 3i. and the latter are disengaged from said bars. This separation draws only a negligible arc, because the current has a shunt path to follow through the interrupter K. Until the interrupter contacts are open, there is only a negligible difierence of potential between the contact bar 3| and the jaws 32 and 33 after the latter separate. When the interrupter contacts open and interrupt the short-circuit current, this potential difierence suddenly rises to the full lineto-neutral voltage of the system. The interrupter contacts cannot open until after the vane llil opens, but they open very quickly after the vane Ilfl completes its 90 swing, at which instant the rods Ill are still in contact with the, arm on the switch 3 and therefore it is essential that the fiashover voltage of the rods ill (lengthwise), plus that of the arms 33, should be safely in excess of the'line-to-neutral voltage of the system. An air blast to accomplish this purpose is supplied through the pipe Ill and the sleeve ill to greatly increase the dielectric strength of thespace surrounding each rod Ill.

When the rods ill reach the end of their travel to the right, the switch 3 is moving at a velocity of about fifty to seventy feet per second, or about six inches in half a cycle, when the sixty cycle per second system is used. It is estimated that the short-circuit current will not be interrupted in less than half a cycle after the vane III is wide open. Therefore, when the line-to-neutral voltage arrives, there will still be a separation of about eighteen inches oi space traversed by the air blast, which provides ample dielectric space to avoid a flashoven' The two blasts of. air along the rods ill assist in maintaining the rapid motion of the switch 3 which swings open about forty-eight inches in another two or three cycles and remains wide open until after the air blast is shut off. Furthermore, since ionization of air and other insulation is a function of time, the air will tolerate for a cycle or two many times the voltage which will flash it over if maintained continuously.

The highest commercial voltage at present is 287 kv. Assuming a voltage of 300 kv., the lineto-neutral voltage is 173 kv., which will flash through about eight inches of still air continuously applied, or through a five inch diameter sphere gap, or through about ten inches for the electrodes described in this specification. I have in my device'about eighteen inches which would probably flash at about 200 kv. (continuous, still air). The air blast will probably raise it to about 350 kv., and the short time in which it operates will probably raise it to over 900 kv.

In the opening movement of the impeller ill, when the contacts 3i leave the jaws 32 and 33, releasing the tension on the link 3], the jaws 32 and 33 continue their clockwise movement in order to increase their separation from the contacts 3|. When the air blast is shut oi! the vane H0 and all of its connected parts are returned to closed position by a torsion spring I32, one end of'which is fastened to the crank H2 and the other end to the casing I22. The jaws 32 and 33, however, stop in horizontal position until the switch 3 releases, when the contacts 3i engage the jaws 32 and 33. The jaws swing up to their closed position, stretching the link 31 and compressing the spring 35 as the contacts 3! turn into their position perpendicular to the jaws 32 and 33. Thereby, there is obtained high-pressure contact with a desirable wiping action which tends to clean the contact surfaces and reduce contact resistance. Rubber bumpers I33 support the rods H4 in proper position to engage the guides 42 on the cross arm 30. A rubber bumper I 34 on the vane ilil stops the latter in open position.

Closure of the switch 3 under the influence of the spring 51 is delayed by flow of air from the air blast in the interrupter K through the pipe 52 and the check valve 55 to the upper end of cylinder 50. Pressure of the air upon the piston 5| resists the-spring and holds the switch open. The instant the air blast is shut off and air starts to rush out of cylinder-55, it lifts the swinging disk 59 to closed position. Leakage of the air through the check valve, however, slowly reduces the pressure in the cylinder 55 and allows the spring to movethe piston upward and move the switch 3 toward closed position. When the pressure in the cylinder 50 has dropped a certain amount, the weight of the valve disk 53 overcomes the air pressure in the cylinder 53, and the disk 53 drops wide open, allowing the remaining air in the cylinder to discharge more quickly and enabling the switch to finish its closing movement more quickly under the action of the spring 51.

The main automatic disconnecting switch and the mechanism for opening and closing it are shown in detail in Figs. 14 and 15. The switch includes a blade I pivoted at one end to swing horizontally on a vertical shaft 23, which in turn is borne by a bracket 23 secured to a corner of the bedplate 20 of the interrupter K. The opposite end of the switch has vertical contacts 55 engageable between contact jaws 56 and 51, supported on an insulator stack 15b and mounted to swing on a fixed vertical pivot 58. Arcing tips 65a and 51a are attached to the contacts 55 and the jaw 51 respectively and are positioned so as to cause the arc to strike from the tip a to the tip 61a instead of from the contacts 55 to the jaw 81 (or 66) and thus save the latter from burning when the switch blade I closes on a short-circuit. Four points or lines of high-pressure electrical contact of low resistance between the contacts 65 and the jaws 66 and 61 are maintained by two compression springs II, the principle being the same as described in connection with the bypass switch 3. The jaws 66 and 61 are connected by the flexible copper braids 18 to the stationary lug I9 and the external circuit connection 19a, all being supported on the insulating support 1917. A flexible conductor 2 connects the switch blade with the jaws 32 and 33 of the by-pass switch 3.

The switch I is shifted by a pneumatically operated mechanism including a cylinder 23 secured to the under side of the bedplate 20 in a horizontal position. A piston 24 in said cylinder has a piston rod 25 extending from one end of the cylinder and with a transverse slot 26 at its outer end. A pin 21 is borne by the switch blade at a point between its ends, and extends through the slot 26, to operatively' connect the piston rod to the blade. An air pipe 2I-2Ia leads laterally from the impeller casing I23 and is in delivery connection with the end of cylinder 23 nearest the switch I. The pipe 2I has a check valve 22 near the casing I23 and opening away from the latter but permitting slow return leakage to the casing. Beyond the check valve the pipe 2Ia also has a valve I5c. Normally this valve is spring-closed, but it is adapted to be opened by a solenoid I5b in circuit with the previously described resistor means of the current interrupter K, as indicated in Fig. 1. The pipe 2 la. also has a by-pass around the valve I50 and provided with a valve I5d.

A vertical insulating tube I2 (see Fig. 14) has, near its upper end, a lateral pipe connection I3 (see Fig. 15) with the end of cylinder 23 remote from the switch. A pipe H (see Figs. 1 and 14) leads from a compressed air storage tank 83k (see Fig. 1) and has delivery connection with the lower grounded end of tube I2 through a valve casing. A valve III controls air delivery from the pipe TI to the tube I2. Said valve is normally closed by a spring I4 but has a projecting stem operable by an electrical coil 69 to open the valve. The tube I2 is rotatable and also vertically reciprocable, for purposes which will appear hereinafter, the tube being supported in stufling boxes for said movements. For rotating the tube there is fastened thereto a lateral crank lb. A link Ia. connects the switch blade I to said crank so that when the switch is swung the tube will be rotated. A switch blade llll, borne by the tube, near the grounded end of the latter, and

extending radially therefrom, is swung by rotation of the tube, for a purpose which will appear hereinafter. This motion of the tube may also be employed to open the circuit containing the coil 69, after the completion of closing motion of the switch I.

The raising and lowering of tube I2 controls operation of the valve lid in the by-pass around the valve l5c of the pipe 2Ia. The valve lid is of a type common for operating whistles. It is spring-closed and has an upwardly projecting stem depressible to open the valve. A lever is pivotally connected at one end at a fixed point on the casing of valve I5d and at its opposite end is pivotally connected to the tube 12. At an intermediate point,said lever is engageable with the stem of valve l5d to depress it. When the tube is in raised position, the valve is spring-closed. Lowering of the tube causes said lever to depress the valve stem and open the valve. Another lever is operatively connected to the lower end portion of the tube 12 and is operable by a toggle 10b to raise and lower the tube. Electromagnets Illa and 10b are employed to operate said toggle. By energizing the electromagnet Illa the toggle is tripped to permit the tube to drop of its own weight about one inch. By energizing the electromagnet 100 the toggle is operated to raise the tube.

For releasing air from the right hand end of cylinder 23 (with reference to Fig. 15), and enable air admitted to the left hand end to move the piston for opening the switch I, there is provided a vent valve 16 for the pipe I3. This valve is normally closed, but it has a stem engaged by a diaphragm I5 subject to pressure in the pipe 2Ia. When air from the air blast flows into pipe 2Ia, the diaphragm is flexed to open the valve I6 to atmosphere.

After the air blast released by the valve 9 has efiected the opening of the by-pass switch and the opening of the interrupter K, it causes the switch I to open. Air flows through the pipe 2|, the check valve 22, the pipe 2 la and the valve I5c to the left end of cylinder 23, with reference to Figs. 1, 15, and 16. Valve I50 is opened by current through the resistor means of the interrupter and the coil l5b connected thereto, by opening of the interrupter. In order to delay opening of the switch I until the shortcircuit current has been interrupted by the interrupter K, the piston 24 is so located in the cylinder, in the closed position of the switch, as to provide a suitable volume which must be charged before the piston is moved to the right. The cylinder space to the right of the piston is vented to atmosphere by pressure of the air in the pipe 2Ia which flexes the diaphragm I5 and opens the vent valve 16. Air pressure at the left of the piston then forces the piston to the right and swingsthe switch horizontally to an open position near the bedplate 20. Opening swing of the switch swings the contacts 66 and 61 to the position indicated by the dotted lines in Fig. 15, The check valve 22 holds air pressure in the left end of cylinder 23 a short time after the air blast has been shut ofi, in order to ensure complete opening of the switch blade I. The check valve has however a slow leak in the reverse direction which permits air pressure to escape from the left end of the cylinder after the switch has been opened, so that the switch may be reclosed within a short time if desired.

The switch I is reclosed by closing a circuit containing the coil 69 and thereby opening the valve III. Air is thereby admitted from the compressed air tank 8010 through the pipes I I I2 and I! to the right end of cylinder 23 to force the piston 24 to the left and rcclose the switch I. As the switch blade recloses, its contacts 65 strike the jaw 66 in a tangential direction in order to relieve the shock of impact and to permit very quick closure of the switch blade, which is very desirable for synchronizing purposes.

In order to prevent the switch blade I from drifting away from its open and closed positions after the air pressure is removed a leaf spring Id lar spring holds the jaws 88 and 81 in open position and in closed position.

The valve l5d, in the by-pass around the valve I5c, is also adapted to function in controlling the operation of switch l, as will be explained hereinafter.

There are three of the valves 8, one for each phase of the circuit breaker. The structure of one of these valves is shown in Fig. 16. It includes a hollow cast iron body or casing 82 with a flange 8| bolted to the compressed air storage tank 8. Said body defines an interior space in constant communication with the interior of the tank 8. The casing is formed with an outlet nozzle 83 extending downward through the space 85 and in direct delivery communication at its upper end with the air blast tube I8. Strengthening webs, not shown, preferably integral with the body 82, may be positioned in the center line of flow of air in the space 85 in such a manner that they do not interfere with the free flow of air. At its lower end the nozzle has a valve seat 84. A disk-like section 88 preferably a bronze casting, forms the lower wall of the casing and is bolted to the casing. A diaphragm is secured ,to the lower section or cover 88 and the two define therebetween a shallow air chamber of comparatively small volume. The diaphragm comprises a rubber disk 88 bolted around its margin to the upper face of the cover 88 and having a central portion comprising an upwardly'dished steel disk 88!! riveted thereto. The rubber portion of the diaphragm is held seated upwardly against the valve seat 84 by air pressufficient pressure to hold the diaphragm against the seat 84 and keep the nozzle closed against admission of compressed air from the tank 8 and ,the space 88. Normally there is only atmospheric pressure in the nozzle, above the diaphragm. Air pressure in the space 85 tending to force the diaphragm downward acts only on the annular area of the diaphragm exposed between the clamping ring 880. and the seat 84.

The diaphragm is forced downward to admit air from space 85 to the nozzle 88 by venting the small chamber beneath the diaphragm. This venting is done very quickly by opening six valves 8| simultaneously. Normally said valves are held closed by electromagnets 8|a with their magnetic circuits in closed position and therefore exerting maximum force. The breaking of the current through these magnets instantly releases them and each of the valves are blown open downwardly by air pressure in the small chamber. This pressure exerts an unbalanced pressure on each valve, which weighs only a small fraction of a pound, resulting in very high acceleration. Each valve comprises a hollow cylinder whose upper edge bears against a valve seat 8"). At its lower edge the valve has an outwardly extending annular flange which bears against another seat 8|d of'annular form and stops passage of air. The internal diameter of the seat 8|d slightly exceeds the diameter of the seat disk 8|) and the external diameter of the cylindrical valve so as to aflord an annular flange area on which the air pressure exerts an unbalanced force tending to open the valve. A rubber ring 8|e may be interposed between the flange 8|c and its seat to reduce leakage and also increase the opening force by its tendency to expand.

The magnet current for the valve 8| is broken by the means shown at the lower right-hand portion of Fig. 16. There, a pair of wires 9|Ic coming from an automatic relay are energized, when the relay is closed, with direct current at volts or 250 volts, for the purpose of opening the circuit breaker. This direct current then flows through a very small electromagnet 8|m which is made so small that it will open in about onetenth of acycle or less, and open its contact tip 8|p. This breaks the circuit through magnets 8|a, which current is supplied continuously by a small local storage battery, preferably of about twelve volts and located at the circuit breaker. The storage battery is maintained in a charged condition by a small rectifier 8|q. A small magnectic blowout coil 8|r reduces duration of the small twelve-volt are as the current is broken The magnetic blowout coil is continuously energized from the storage battery, with a small fraction of an ampere. Connected to one only of the eighteen electromagnets (six for each phase of the circuit breaker) is a spring contact 8 Is which is opened by the opening of the magnet 8 a, thereby breaking the current through the magnet 8|m. This permits the contact 8|p to reclose, reenergizing the eighteen magnets and closing the eighteen small valves. The air pressure, having been exhausted, is not available to resist such closing.

Air under pressure is supplied from the tank 83k to the small chamber beneath the diaphragm through an upwardly opening check valve 88L Air is also fed to said chamber from the valve space 85 through a spring-pressed feed valve to compensate for leakage from the chamber, as'will be explained hereinafter.

The diaphragms of the three valves 8 are automatically moved to closed position to shut off the air blast on the three phases by means operable in response to the air blast itself. As shown in Fig. 16, a pipe 83a is tapped into the air blast outlet 83, and is in delivery connection to the right-hand end of a cylinder 880. A piston 83b in said cylinder is urged toward the right by a spring 83:! and has a rod connected to a slide valve 88f in a chamber 8811 of the cylinder. Compressed air ls supplied to the chamber 83h from the tank 88k and the latter is supplied through a pipe and a check valve 88m from a main source of compressed air. Said source, not shown, also supplies air to the tank 8 through the check valve 8a. Air pressure from the blast forces the piston 88b to the left against the resistance of the spring and moves the slide valve to uncover the port 889' in the charged chamber 83h. Compressed air is thereby admitted through the pipes 88i and 8314. and through the check valve 832? to force the diaphragm to closed position and shut off the air blast. The air blast reduces the pressure in the tank 8 by about twenty pounds per square inch in about one second. Hence the pressure per square inch in the tank 83k and therefore under the diaphragm is about twenty pounds per square inch greater than that on top of the diaphragm which tends to keep it open.

to closed position. If the air pressure under the diaphragm exceeds by twenty pounds per square inch that on top of the diaphragm the check valve is forced open and allows air to flow to the space 85. Thereby the difference in pressure upon the rubber disk is limited to twenty pounds per square inch to prevent injury to the disk. This condition arises only when the tank 8 is being charged after being completely emptied for any purpose. In preparation for recharging, a globe valve 83:; is opened by hand to admit air from cylinder chamber 83h through pipe 83p to the pipe 83i to hold the diaphragm closed'until the tank 8 is recharged to normal pressure, after which the globe valve is closed by hand. Closing by hand of the valve 831 prevents air from flowing backward to atmosphere while the valve 831 is open. Only one set of parts numbered 83a to 831 may serve to operate the three air blast valves 9 of the breaker.

A header pipe 835 connects the three pipes 83a and the check valves 831? to one pipe 831'. The diameter of said header pipe 83:: is selected so that its volume will give the correct time delay between the'opening and reclosing of the three air blast valves, allowing ample time for the interruption of the main line current, but no unnecessary time which would be wasteful of the air supply and delay restoration of normal pressure to the tank 8.

After the air blast is shut off the spring 83d in the cylinder 83c moves the piston 83b and the slide valve 83 to the right to shut off the air supply from the pipe 83a and header 83s and exhaust the ai'. in them to atmosphere. This avoids a rush of air through the admission check valves 83t of the valves 9 when the vent valves 9| open, which would delay the opening movement of the diaphragms 99.

In order to further reduce the opening time of each diaphragm the pressure therebeneath may be reduced below the pressure thereabove. Such reduction is permissible because the pressure beneath the diaphragm acts upon a much greater area than the pressure above, in the closed position. The air pressure beneath will be exhausted much more quickly if its initial pressure is less. Hence the diaphragm will start to open earlier and the total opening time of the entire valve will be thereby shortened. The desired pressure pen squareinch under each diaphragm is maintained automatically by an adjustable pressure-regulating valve which takes air pressure from the main tank 8 through an air duct 90c acting on a small piston 99g against a spring 90 which is adjusted by a screw 90d. The air pressure in the duct 99c pushes the piston 909 down until the air escapes through the duct 9071. into the chamber beneath the diaphragm. Lowering the screw 99d will increase the pressure under the diaphragm" and raising the screw will decrease the pressure. There is always a slight unavoidable leakage through the valves 9 I. Passage of air through the ducts 90c and 99h compensates'for said leakage, and for a given rate of flow the pressure drop through these ducts depends upon the width of opening of the piston 909, which depends upon starting the rise of direct current through the trip coil of the circuit breaker, the opening time ending when at the instant the main contacts of the circuit breaker open and interrupt the high tension current. The fastest relay available for such service, although designated as instantaneous; actually consumes a. minimum of about a sixtieth of a second between the starting current and the closing of the relay contacts. In a large percentage of said cases the so-called instantaneous" relays cannot be used, such as cases where relays must delay to allow other relays closer to the system fault to open first and clear the fault from the system. Hence, in a large percentage of cases there is a more than one cycle (referring to the common frequency of sixty cycles per second) between the occurrence of the short circuit and the closing of the relay contacts. Advantage may be taken of this fact to start the air blast breaker, of the type helein describedbefore the closing of the relay contacts, thereby reducing the opening time of the circuit breaker and reducing the total duration of the short circuit. This is accomplished by the coordinated action of the circuit breaker contacts, the impeller vane H or the mechanism M, and an auxiliary by-pass valve 92. The valve 92 is opened by an alternating circuit magnet coil in series with a secondary winding of the main current transformer and therefore is energized at the first half cycle of the short-circuit current, which time is one or more cycles before the relay contacts close and energize the coils Bid to open the air blast valve 9.

The by-pass valve 92 appears in Figs. 1, 16, and 17 and is shown in detail in the last-mentioned view. The valve includes a rubber diaphragm 92a which normally closes a passage 92b leading from the constantly charged air space 85 of the valve 9 to the interior of the nozzle 83. At the outer side of the diaphragm there is a metallic valve body 92d whichforms with the diaphragm a chamber 92c. The valve body has vent ports Me which are normally closed by a movable ring 92f fastened to a sleeve 92g and an armature 92h. The armature is moved by a magnet pole 922' energized by an alternating magnet .coil 927' which is in series with a secondary coil of the main current' transformer 5. Through piping leading from the tank 83k to an air duct 92k of the valve 92 air'pressure is supplied to the chamber 92c to hold the diaphragm normally in position to close the passage 92b. The air duct 92]: is in the stationary stud 92m secured to the valve body 92d and the magnet pole' 92!. The sleeve 92g slides easily on the stud 92m. F'lat springs 92p normally hold the movable ring 9! closed. When said ring is moved to open position by the magnet coil 927' the chamber 92c is vented and the air pressure in the main valve space 85 forces the diaphragm 92a to open the passage 92b and admit air from space 85 and the connected tank 8 to the nozzle 93.

The opening of the by-pass valve 92 discharges compressed air from the tank 8 tothe nozzle 83 and the connected air blast conduit l9 and starts to build up pressure in the blast conduit. This preliminary pressure starts the opening movement of the impeller vane Ill and the by-pass switch 3. One or more cycles later, when the diaphragm 90 of the main valve opens, releasing the air blast, there is already a certain pressure in the blast tube In and vane III! has already started to move. ing the wave of air pressure by several feet in its upward travel and thereby advancing the instant when the main breaker contacts are blown apart. Circuit breakers of this class should have an This is equivalent to advanc-.

opening time of as short as three cycles, or shorter if possible. Therefore an improvement of only a quarter of a cycle, for instance, is of practical importance and commercially valuable.

when the fault on the power system is at such a location that this circuit breaker is required to remain closed even though the short-circuit current passes through it, to allow some other breaker to clear the fault, the by-pass valve 92 will open but will close again at the instant that the short circuit is cleared by the other breaker. The relay controlling this breaker will not close and the mainair blast will not be released. The vane III will be moved until it opens the air passage in conduit III wide enough to relieve the air pressure under it and then stop. When the by-pass valve 92 closes, the vane IIO closes and also the by-pass switch 3. The air admitted by the valve 92 is insuiiicient to open the breaker contacts in the interrupter K. Even though the switch 3 opens momentarily and recloses no harm is done because the main circuit is not opened. The contacts in the interrupter are shunted around the switch 3 and are capable of carrying the short-circuit current for such a short time without, overheating. The main switch I does not open because the air connec-- tion for opening it is tapped into the air blast tube above or beyond the vane Ill, where the pressure from the valve 92 is too slight to open Iihe switch I.

A general wiring diagram, for the three-phase circuit breaker is shown in Fig. 18. The current flows along the main automatic disconnecting switch I, the flexible conductor 2, the by-pass switch 3, the flexible conductor 4 and the current transformer 5 and out to the main line. The

, transformer i has three separate magnetic circults each with one secondary winding. One of these secondary windings is used to operate the coil "7 to open the by-pass valve 92 and expedite the opening of the high-tension circuit by a preliminary supply of air pressure to the blast conduit III. Another secondary winding is used to operate any well-known type of relay I00, .to open the circuit breaker by opening the valve 9. When the valve I opens, a blast of compressed air'rushes up through the tube Ii, blows open the by-pass switch 3, then opens the contacts of the interrupter K (thus interrupting the hightension circuit) and then opens the main switch I. The closing of the valve 9 shuts off the air blast. and springs return the by-pass switch 3 and the interrupter horns I6 to closed position. The main switch I remains open. The third secondary winding of the transformer is used for additional relaying or metering functions in accordance with common practice.

There are three small knife switches III. If all of these switches are open' each of the three relays Ill for the three' phases, will affect only the valve 9 on its own phase and if the short circuit is on only one phase (from line-to-neutral or ground), then only one pole of the breaker will open. If the switches iii are closed the operation of any relay will open all three valves 0, opening all three poles of the breaker. The three poles of the breaker may also be opened manually by closing the three knife switches IIII and one control switch I". Or, one pole only may be opened by closing only one of the switches Ill and then switch I02. The three poles of the breaker always close together by closing the control switch Ill, energizing the three coils 6! which cause the three main automatic switches I to close.

Alongside of the control switches I02 and I03 on the switchboard are three miniature red lamps and three green lamps to indicate whether the switch I on each phase is in closed, open or intermediate position (an improper position requiring remedy). A double throw switch I04 is operated by the rotation of the tube 12 on each pole of the breaker to operate the red and green lamps.

In a three-pole breaker of this class it is never desired to close one pole without the other two and it is desirable to close all three poles simultaneously. Therefore the preferred arrangement is to have one coil 65 and valve I0 apply air pressure simultaneously to the three tubes 12, each closing its main switch I. Under certain conditions, however, it has been considered desirable to have a circuit breaker which could open one pole on a short circuit on that phase (to ground) without opening the other two phases, in order that motors may continue to run for a few seconds until the breaker may be reclosed, as in case the short circuit is only momentary, such as a flashover due to lightning. This circuit breaker, as already described is readily adapted to single-pole opening.

A large percentage of the faults on power systems are of a transient nature, such as a flashover due to lightning. The are of the fiashover being extinguished by the quick opening of the circuit at its source of power, it is very desirable to reclose the circuit as quickly as possible in order to prevent customers motors from tripping out. With the various types of circuit breakers heretofore used it is necessary to open the circuit breaker completely in order to set in motion the reclosing means. This requires a minimum of about 45 to 60 cycles of time (60 cycles per second). In my circuit breaker the construction is such that the circuit can be reclosed in about cycles of time. This is accomplished by providing the valve I50 (Fig. 15) which is normally held closed by an internal spring, thus preventing the flow of air through the pipe 2Ia into the cylinder 23 to open the switch I. The switch I thus remaining closed, the interrupter horns I6 are quickly reclosed by their springs when the air blast is shut 011, thus reclosing the high-tension circuit quickly. In order to reclose the horns as quickly as possible, the valve reclosing means, from 83;; to 8311. inclusive, may be provided separately for each of the three poles of the breaker, eliminating the header pipe 83s, with its volume designed to regulate the time of releasing of -the main diaphragm 90 (Fig. 16).

If the fault remain on the circuit immediately after the breaker has opened, it is very desirable to avoid reclosing of the breaker and a consequent second shock and disturbance to the remainder of the power system. It is possible to accomplish this by utilizing the circuit through the potential equalizing resistors I5 (Fig. 5). As previously mentioned, an electromagnet lib is connected in series with this circuit, as shown in Fig. 1. When this magnet is energized it opens the valve I5c allowing air to pass and open the switch I in case the fault is still on the circuit. If the fault has been removed the current through the magnetic coil I5b is insuflicient to open the valve I50, against its spring resistance. Therefore no air passes, the switch I remains closed and the horns I6 close, completing the high-tension circuit again.

Long high-tension transmission lines have a relatively large electrostatic capacitance, which, in series with a high resistance such as the resistors 15' would be diflicult to distinguish (by the charging current is reduced sharply after the first half cycle of unidirectional current so that it will be much less than the current which would continue to flow if there is a fault remaining on the line. The electromagnet can therefore be designed and adjusted to distinguish between charging current and a line fault.

An alternative expedient for distinguishing between fault current and-charging current is to reduce the ohms in resistors I 5' resulting in increased fault current. This fault current (through resistors l5) must be interrupted by the switch I at its contacts 61a. To assist in interrupting this small current, compressed air may be taken from the air blast tube l0 and carried 5 via the switch I to the contact Gln.

There are occasions when it is necessary to open the 'circuit breaker (non-automatically) and leave it open, though there is no fault on the line. The valve I511 is provided to enable this. It by- 0 passes valve I50 and allows air to pass and open the switch I; The valve lid, and adjacent parts being at the line potential, its operation is controlled by vertical movement of the insulating tube 12 (Fig. 14). When the tube 12 is in its ielevated position the valve I Set remains closed l by its spring and the breaker is set for automatic reclosure. To suppress the automatic reclosing feature the valve lid is held open by energizing the electromagnet Illa to trip the toggle b and 3 allow the tube to drop. The automatic reclosing feature is re-established by energizing the'electromagnet file. The insulating tube I2 thus performs three independent functions: the one just described, and the two other functions previously described. None of these functions inter feres with the others. The vertical movement is permitted by link In being long in relation to the small vertical movement, the connections not being tightly fitted. The casing of valve 10 is rigidly fastened to the grounded structure supporting the interrupter bedplate 20 on the insulator stacks. That rigidly fixes the distance between the valve 10 and the bedplate 20 with attached parts.

3 Provision is made for using the circuit breaker to test the line to determine whether there is a fault on the line, without subjecting the remainder of the power supply system to a shock in .casethere is a fault on the line when so tested. For this purpose there is provided for one of the switches I a contact midway between the open and closed positions of the said switch. This contact, designated lllla, is wired in multiple with switch I02, the opening control switch of the breaker. To make the test, the operator closes the switch I03, starting the switch I on its closing movement. When the switch I reaches its midposition the switch I04 contacts the member lfla tripping open the three air blast valves 9, opening the interrupters and holding them open while the switch I completes its closing stroke. If there is no fault on the line the switch I remains closed (and the interrupters close in either case). If there is a. fault the switch I iopens before the interrupter K recloses, and

there is no shock to the system. After the test the operator opens the switch lllla and leaves it open. The contact 104a is arranged to contact only in the closing direction of the switch blade I04, not in the opening direction.

Certain features of the apparatus disclosed but not claimed herein are claimed in my co-pending patent application Serial No. 732,737 filed June 27, 1934. V

. What I claim is:

1. In an electrical circuit having control mean therefor including a current interrupter operable by a blast of gas to break the circuit and a disconnecting switch in series with the-interrupter,

v a gas-pressure mechanism to operate said intermeans to control the duration of said blast automatically, a gas-pressure-responsive device to operate the disconnecting switch to open position, and a gas delivery connection between the blast conduit and said device to conduct gas pressure of said blast from the conduit to said device to open the disconnecting switch after the circuitbreaking operation of the interrupter by the blast and during the duration of the blast.

2. In an electrical circuit having control means therefor including a current interrupter operable by a gas blast to open the circuit, a transfer switch in shunt with the interrupter to normally conduct the current past the interrupter, and a disconnecting-switch in series with the interrupter, a gas-pressure apparatus for operating said interrupter, said transfer switch and said disconnecting switch, comprising means responsive to abnormal current in the circuit to supply a blast of gas to the interrupter to operate it to open the circuit, means responsive to said blast to open the transfer switch prior to opening of the interrupter by the blast to thereby transfer the current to the interrupter for breaking by the latter, means responsive to the blast to open the disconnecting switch after opening of the interrupter by the blast, means to automatically reclose the transfer switch, and means responsive to the gas blast to delay reclosure of the transfer switch until after the disconnecting switch has been opened a safe distance in response to the as blast.

3. In an electrical circuit having control means therefor including a current interrupter operable by a gas blast to open the circuit, a transfer switch in shunt with the interrupter, and a disconnecting switch in series with the interrupter, a gaspressure apparatus for operating said interrupter, said transfer switch and said disconnecting switch, comprising means responsive to abnormal current in the circuit to supply a blast of gas to the interrupter to open it, means responsive to said blast to open the transfer switch prior to opening of the interrupter by the blast to thereby transfer the current to theinterru'pter for breaking by the latter, means responsive to the blast to open the disconnecting switch after opening of the interrupter by the blast, means to automatically reclose the transfer switch, means responsive to the gas blast to delay reclosure of the transfer lwitch until after the disconnecting 

